The Dana-FarberCancer Institute, in collaboration with the Service Employees International Union, proposes the Breast Cancer Education Project (BCEP) toassess the effects of a worksite breast cancer education program targeted toward low-income women and women of diverse ethnic/cultural groups. The purpose of this program is to raise awareness of breast cancer, enhance knowledge of the importance of early detection, and increase adherence to mammography screening guidelines among underserved women. The BCEP employs a Peer Health Adviser model in which members of the target community are recruited and trained to provide health education and outreach. This model emphasizes the importance of culturally relevant intervention programs, the function of social networks in promoting behavior change, and the need for employee involvement in sustainable worksite education programs. In this study, a randomized controlled design is used in which worksites are the unit of randomization, intervention and analysis. Thirty worksites, recruited to the study through SEIU, will be randomly assigned to intervention or comparison groups. The primary outcome variable examined will be mammography practices and compliance with recommended screening guidelines over time. These variables will be assessed among women aged 52-63 through administration of a Health Habits Questionnaire. Intrapersonal, interpersonal and institutional factors influencing breast cancer screening behaviors will also be assessed, based on surveys of employees, management and union representatives. A process evaluation wil assess the extent to which the intervention was implemented and the costs associated with implementation. The Breast Cancer Education Project stands apart from other worksite education programs as a theory-driven model with an innovative approach to constructing culturally and linguistically appropriate programs for underserved women. Collaboration with the SEIU provides a unique opportunity to access service worksites and their employees, and to build on previously-established educational strategies used by labor in communicating effectively with their membership. Products of this study will include a tested worksite intervention model for use within an ethnically diverse population, and an implementation manual with program materials for use in other worksites.